Сломанный QR-код (Broken QR code)

hackerlab

Task: a Version-4 QR code with an oversized opaque spider/shield logo covering the center; all standard decoders fail. Solution: rebuild the 33x33 module matrix, BCH-decode format info, de-interleave 4 blocks, Reed-Solomon erasure-decode the readable blocks, then recover the logo-covered block via per-bit reliability + EC-constrained brute force, and verify by full-symbol re-encode against all reliable modules.